Partial eclipses — which resemble a bite taken out of the sun — will be visible from Iceland, Greenland, Europe, North Africa, western and eastern Asia, ending at 1150 GMT.

London will have its deepest eclipse since 1999, with 85 percent of the sunlight blotted out.

The celestial ballet will on Saturday result in major tides most perceptible in Canada’s Bay of Fundy, on the French Atlantic coast, in the Channel and North Sea — but even the Mediterranean will feel the difference.

France’s Navy Oceanic and Hydrological Service (SHOM) has warned thrill-seekers to beware when the tide sweeps around Mont Saint-Michel, the ancient abbey-island located on the coast of Normandy.

Saturday’s tide on the long, sloping estuary of the River Couesnon at the popular tourist spot will be a whopping 14.15 metres (46 feet) — the height of a four-storey building. The average tide there is 10.5 metres.

While this is incorrect, said Weber, “it will come in faster than a running man. It will be dangerous to venture out too far.”

Horsburgh, from Britain’s National Oceanography Centre, said Saturday’s tide would be several centimetres (inches) above last year’s maximum overall, and in some places may even be slightly surpassed this September, which will also be an equinox, when high water occurs.

Weather is a big influence on a tide’s fierceness — gales can whip up surges able to test the mighty barriers that protect the Netherlands and London from flooding.

“A storm surge can elevate water levels by around four metres in the North Sea on the Dutch coast and tend on the east coast of Britain and the Thames estuary to be around two, two-and-a-half metres in the event of a bad storm,” Horsburgh told AFP by telephone.

In 2010, a sea surge, driven by a storm called Xynthia, flooded parts of the Vendee coast on France’s Atlantic seaboard, killing 41 people.